The present invention relates to a control system for construction machines such as hydraulic excavators, and more particularly to a locus control system for construction machines which enables a bucket tip, for example, to be moved along a target locus.
A prior art control system for construction machines is proposed in, e.g., International Patent Laid-Open WO 95/30059.
According to the above prior art, in an area limiting control system for hydraulic excavators, an area in which a front device is allowed to move is set beforehand, and a control unit calculates a position and posture of the front device based on signals from angle sensors and also calculates a target speed vector of the front device based on signals from control lever devices. Through the calculation, the control unit maintains the target speed vector as it is when the front device is within the set area away from its boundary, modifies the target speed vector to reduce a vector component in the direction approaching the boundary of the set area when the front device is within the set area near its boundary, and modifies the target speed vector to return the front device to the set area when the front device is outside the set area. In this way, the conventional control system intends to perform excavation in a limited area efficiently and smoothly.